1. Field of the Invention
The present invention relates to magnetohydrodynamic (MHD) generators, and more particularly to a staircase electrode-wall configuration for MHD generators.
2. Description of the Prior Art
MHD power generation is of interest for the production of large amounts of electricity. However, MHD generators have a limited lifetime due to electrode-wall erosion which hampers their practical application. The electrodes function in a high temperature, corrosive environment, resulting in chemical reactions, arc spots, etc. which erode and otherwise cause failure to the electrodes. This necessity to prolong electrode and insulator lifetimes in the MHD generator environment has resulted in a variety of electrode-wall designs (see for example Heywood and Womak, Open--Cycle MHD Power Generation, Chapter 7, Pergamon Press, Oxford 1969).
A typical electrode-wall configuration is shown in FIG. 1 where the electrodes alternate with insulators, with the electrode face flush with the inner wall of the MHD duct. The current, J, flows from the anode to the cathode in the presence of the magnetic field, B, and the hot gas flow. The current causes arc spots at the cathode, particularly, and together with the turbulent hot flow this results in chemical reactions at the electrode/insulator interfaces which erode the electrodes. Also, the hot plasma may deposit seed or slag which disrupts the electrode function.